1. Field
Apparatuses consistent with example embodiments relate to an integrated circuit device and signal processing technology in the integrated circuit device.
2. Discussion of Related Art
ISO/IEC 7816-3 defines the standard for a response when a reset signal from an interface device (IFD) is applied to an integrated circuit (IC) chip. According to the standard, if the reset signal is received while power and a clock are being supplied to the IC chip, the IC chip needs to transmit an answer-to-reset (ATR) signal to the interface device within 400 to 40,000 clock cycles. The ATR signal is a string of 32 or fewer bytes. If the ATR signal is not output by the IC chip within that specified period, the interface device deactivates communication with the IC chip.
Some IC's, however, have a tamper-resistant device (TRD) feature. A TRD IC chip is configured so that any code stored in its internal non-volatile memory (NVM) cannot be read. Therefore, when a TRD IC chip is shut down, it is difficult to diagnose the cause for the chip's shutdown and therefore difficult to verify the integrity of the main code. Likewise, even in the situation in which a specific code is intentionally inserted into an IC chip for the sake of identifying intellectual property in the IC chip or the like, the TRD feature prevents such a code from being read, even through an external interface.